This is a cross-sectional, controlled study designed to investigate whether Transforming Growth Factor-beta (TGF-beta) mediates increased asthmatic epithelial susceptibility to respiratory syncytial virus (RSV) infection by examining responses to RSV infection in epithelial cells cultured from asthmatic and non-asthmatic participants. Non-smoking healthy adults and mild asthmatics, aged 18-60 years old, will be recruited to participate. Potential participants will be prescreened and scheduled for a final eligibility visit that will include medical history review, vital signs, physical examination, blood draw, and pulmonary function tests (PFTs). After eligibility is confirmed, the participant will be scheduled for bronchoscopy. During the bronchoscopy, bronchial epithelia and alveolar macrophages will be obtained from the participant for analysis. Alveolar macrophages will be evaluated ex-vivo for inflammatory activity at baseline and after stimulation.